This invention relates to a mower for use in harvesting crops.
One type of conventional tractor-drawn mower comprises a series of cutting discs mounted rotatably to the chassis of the mower in a row at right angles to the direction of movement of the mower as it advances through the crop. The discs are usually provided with peripheral cutting elements with the circular cutting paths of such elements on adjacent discs usually being arranged to overlap so that the discs cut a complete swathe of grass between them without leaving a ridge of unmowed grass behind the mower. Complicated and expensive synchronisation means or gearboxes have thus been required on such mowers to ensure that overlapping elements do not come into contact with each other as they rotate about their respective axes. Clearly, much damage would be caused to the mowing machine should two cutting elements collide with each other. However, even when synchronised, it is possible for one of the rotating discs to hit an obstacle, such as a small rock or boulder for example, and to be thrown out of synchronisation which may lead to even further damage of the cutting elements or mower, and also may require the mower operator to stop the mowing operation and re-synchronise the disc. This of course wastes time and is a laborious process.
Previous attempts to avoid the necessity of having synchronisation means have included arranging the cutting discs at different heights so that the cutting elements disposed on the periphery of the disc rotate in different planes. However, these methods suffer the disadvantage that the crop or grass is not cut uniformly even and the lower elements tend to cause unsightly "scalping" when coming into contact with slight undulations or contour differences in the field. In commercial crop harvesting applications where profit margins are important, many farmers consider a large cutting height discrepancy to be unacceptable as this leads to crop wastage and loss of profits.
Another type of conventional machine for cutting grasses recreational areas and the like employs rotating blades or "slashers" to cut through the grass. Such machines clearly have no application in harvesting applications where the crop is sought to be recovered in a more or less undamaged state. Indeed, in such conventional grass cutting machines it is only by coming into contact with the rotating blades several times that the grass is cut finely and thrown clear of the machine. In crop harvesting applications, it is exactly the opposite effect which is required. Ideally, the stalks of the crop which is to be harvested should be cut only once so that a following bailing machine is able to lift and recover the cut crop.
Various types of gang mowers have also been proposed which employ a plurality of cutting blades which are arranged in several parallel rows which extend at right angles to the direction of advancement of the gang mower through the grass. Once again, these types of machine are not suitable in harvesting applications as the front row of cutting blades throws cut material into the path of the rearward row of cutting blades which only serves to cut the mown material more finely. In harvesting applications, the aim is to prevent further damage to the cut material as far as possible.
Many commercial farmers employ tractors for drawing large agricultural implements and machinery around their farms. It would therefore be advantageous when designing a mower to design a machine which can be drawn behind a tractor and is able to draw power from the tractor.
The present invention seeks to address these requirements.